This application is based on and claims priority under 35 U.S.C. sotn. 119 with respect to Japanese Applications No. 2002-188487 filed on Jun. 27, 2002 and No. 2002-221596 filed on Jul. 30, 2002, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a laminated optical waveguide array, a beam collecting device and a laser emission device for collecting laser beams to a target position on an article to be processed.
2. Discussion of the Related Art
FIG. 16 shows a general construction of a semiconductor laser beam collecting device known as prior art. The semiconductor laser beam (hereafter referred simply as xe2x80x9claser beamxe2x80x9d) 2 is emitted from a beam emitting part 12 on an active layer of a semiconductor laser (such as a laser diode or the like) and takes the form of an elliptical in the section normal to the direction in which the laser beam 2 travels. The laser beam 2 of the elliptical form has a fast axis direction and a slow axis direction. The longer the elliptical form is distanced from the beam emitting part 12, the larger it becomes. There has been known a semiconductor laser beam collecting device of the type wherein laser beams emitted from a plurality of beam emitting parts which are arranged in a second-order matrix extending in the fast axis direction and in the slow axis direction are collected by optical fibers of a fewer number to reinforce the output of the laser beams.
For example, where the semiconductor lasers are to be employed as a power source for a laser machining apparatus or a laser material processing apparatus, it must be of a high power. The laser beam emitted from a single beam emitting part is weak in power strength. Thus, a group of lenses are used to collect laser beams emitted from a plurality of beam emitting parts thereby to strengthen the output of the laser beams.
Japanese unexamined, published patent application No. 2000-98191 discloses a semiconductor laser beam collecting device shown in FIG. 16. In the application, it is proposed to collect laser beams to optical fibers thereby to strengthen the beam output power by utilizing a group of lenses and the optical fibers 30 and arranging a fast axis direction collimation lens array 70, a fast axis direction collective lens 80 and a slow axis direction collective lens 90, in turn within a very short space from the beam emitting parts 12 to the optical fibers 30.
In order that laser beams emitted from semiconductor laser emitting parts are collected efficiently to optical fibers thereby to strengthen the output power of the laser beams, it is necessary to gain the density of the beams by entering the beams from many numbers of the emitting parts into much finer optical fibers and to enter the beams efficiently into the optical fibers by entering the beams into the incidence surfaces or surfaces of the optical fibers at a smaller or gentle incident angle, namely, at an angle as close as the right angle to the incidence surfaces without reflecting the entered laser beams outside.
The laser beams coming from the emitting parts 12 advance as they spread in the fast axis direction as well as in the slow axis direction. For collection of the laser beams which advance as spreading, the lenses used therein and the arrangement of the same are to be quite highly precise.
In the semiconductor laser collecting device known heretofore (e.g., from the aforementioned Japanese patent application No. 2000-981919), the emitting parts are arranged with a relatively wide space in the fast axis direction, and correcting the beams in that direction is carried out with the fast axis direction collecting lens 80 once they are transformed with the fast axis direction collimation lens array 70 into parallel beams. On the other hand, the emitting parts 12 are arranged with a relatively narrow space in the slow axis direction, which requires that the lenses used be very small in diameter and difficult to arrange. Thus, collecting the beams in the slow axis direction is carried out with the slow axis direction collecting lens array 90 without transforming the beams into those parallel.
That is, in the prior art device mentioned above, the space between the slow axis beam collective lens array 90 and the emitting parts 12 is short, e.g., several millimeters at most. It is therefore difficult to arrange the fast axis direction collimation lens array 70 and the slow axis direction beam collective lens array 90 properly within the short space. The optical fibers 30 are caused to be arranged within a short distance from the emitting parts 12. Thus, where the incident angle (xcex8outx) in the fast axis direction is set small, the number of the laser beams which can be collected in the fast axis direction is made small, so that it cannot be practiced to obtain high power laser beams from a large number of optical fibers for use in laser machining.
It is therefore a primary object of the present invention to provide a laminated optical waveguide array, a beam collecting device and a laser emission device capable of collecting many numbers of laser beams for a higher power output.
Another object of the present invention is to provide a laminated optical waveguide array, a beam collecting device and a laser emission device capable of restraining laser beams from shining therethrough thereby to enhance the laser collecting efficiency.
Briefly, according to the present invention, there is provided a laminated optical waveguide array comprising: a plurality of plate-like optical waveguides made of a material having a predetermined refractive index; and a plurality of spacer members having a lower refractive index than that of the optical waveguides and arranged alternately with the optical waveguides.
With this configuration, a spacer member is interposed between two adjoining optical waveguides, so that the dimension in the space between the adjoining optical waveguides can be set precisely and easily. In particular, since the spacer members are made of a material having a lower refractive index than that of the optical waveguides, the laser beams traveling within the optical waveguides is restrained from coming therethrough, so that th beam collecting efficiency can be enhanced. Preferably, optical fibers may be utilized as the spacer means as described in one form of the embodiments. Since optical fibers in the market have various outer diameters machined precisely and are easily available. Therefore, by selecting the optical fibers properly, the spacer members for the optical waveguides can be made easily and at a lower cost. Spacer balls and plate members may be utilized as the spacer member as described in other forms of the embodiments.
In another aspect of the present invention, there is provided a laser emission device comprising: a semiconductor laser array having a plurality of laser emitting parts which are arranged in a fast axis direction as well as in a slow axis direction each for emitting a laser beam of an elliptical cross-section which spreads in the fast and slow axis directions as it travels; a plurality of optical fibers; a collective lens; and a laminated optical waveguide array composed of a plurality of plate-like optical waveguides made of a material having a predetermined refractive index and a plurality of spacer members having a lower refractive index than that of the optical waveguides and arranged alternately with the optical waveguides. The waveguide array is arranged between the semiconductor laser array and the plurality of optical fibers for collecting laser beams emitted from plural laser emitting parts of a group separated from other groups in the slow axis direction, to one of the optical fibers aligned thereto. The collective lens further collects the collected laser beams from all of the optical fibers and concentrates them to a target position.
With this configuration, a plurality of laser beams emitted from the semiconductor laser array are collected separately by plural optical wave guides, and the laser beams collected by each optical waveguide is further collected through the optical fiber to the collective lens, so that laser beams collected in a high density can be concentrated onto the target position.
In still another aspect of the present invention, there is provided a beam collecting device comprising: an optical waveguide for collecting a beam entered into an incidence surface thereof to a predetermined position in a predetermined direction and for emitting the a beam from an emission surface of an optical fiber; and refraction means provided between the optical waveguide and the optical fiber for diminishing the angle which the beam refracted at the incidence surface of the optical fiber makes with the axis of the optical fiber, in comparison with the angle which the beam before being refracted at the emission surface of the optical waveguide makes with the axis of the optical fiber.
With this configuration, the refraction means diminishes an acute or larger angle of a laser beam relative to the lengthwise direction or the axis of the optical fiber so that the laser beam is entered into the optical fiber at a gentle or smaller angle. Thus, a larger number of laser beams can be collected by the optical waveguide in a miniaturized system, but the incident angles of the collected laser beams to the incidence surface of the optical fiber are diminished or reduced. This advantageously restrains the laser beams traveling within the optical fiber from coming through the same, so that not only the miniaturization of the system can be realized, but also the beam collecting efficiency can be enhanced.